Moussa Dadis Camara, a former army captain who led the coup last month and declared himself the country's new president, signed the decree to form the government on Wednesday "upon the recommendation" of Kabine Komara, the prime minister.
Komara, a Guinean banker who had been living in Cairo, was named prime minister on December 30 by Camara's National Council for Democracy, presumably based on recommendations labour unions had made to the previous government in 2006.
Camara has pledged to step down and hold elections in 2010, after tackling widespread corruption.
The coup appeared to receive popular support inside the country after 24 years of authoritarian rule under Conte.
But the African Union has suspended Guinea's membership in the block, giving the coup leaders six months to restore "constitutional order" or face further sanctions.